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EP0211161B1 - Réserve lithographique et procédé l'utilisant - Google Patents
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EP0211161B1 - Réserve lithographique et procédé l'utilisant - Google Patents

Réserve lithographique et procédé l'utilisant Download PDF

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Publication number
EP0211161B1
EP0211161B1 EP19860106714 EP86106714A EP0211161B1 EP 0211161 B1 EP0211161 B1 EP 0211161B1 EP 19860106714 EP19860106714 EP 19860106714 EP 86106714 A EP86106714 A EP 86106714A EP 0211161 B1 EP0211161 B1 EP 0211161B1
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EP
European Patent Office
Prior art keywords
resist
poly
silicon
image
polysulfone
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Expired
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EP19860106714
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German (de)
English (en)
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EP0211161A1 (fr
Inventor
Ranee W. Kwong
Harbans S. Sachdev
Krishna Gandhi Sachdev
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International Business Machines Corp
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International Business Machines Corp
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004—Photosensitive materials
    • G03F7/075—Silicon-containing compounds
    • G03F7/0757—Macromolecular compounds containing Si-O, Si-C or Si-N bonds
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004—Photosensitive materials
    • G03F7/039—Macromolecular compounds which are photodegradable, e.g. positive electron resists

Definitions

  • the present invention relates to lithographic resists and methods of using the same.
  • resist materials capable of smaller image dimensions, e.g., 1 ⁇ m or less, with high sensitivity to exposure radiation including electron beams, X-rays, uitravioiet or excimer lasers, etc.
  • High energy, shorter wavelength radiation such as deep-UV (220-290 nm), because of reduced diffraction effects, offers the possibility of high resolution imaging. Accordingly, there has developed substantial interest in the art in the use of deep-UV and an interest in designing resist materials sensitive to deep-UV radiation. Specially designed new materials for such applications are required since conventional resists are optically clear below 300 nm.
  • the various X-ray exposure sources useful in X-ray lithographic techniques include electron beam anode, pulsed plasma and electron storage ring emitting synchrotron radiation, the last source being known to be the most powerful source of highly collimated and intense radiation.
  • the most accessible and the cheapest sources based on electron beam evaporation provide relatively weak X-ray emissions. Therefore, for practical applications of X-ray lithography in the fabrication of highly dense integrated circuit devices, the art has desired that highly sensitive resist materials be developed which also have the necessary thermal stability, resistance to dry processing (such as reactive ion etching and metal evaporation) and good adhesion to various organic and inorganic contacting surfaces to make the same useful for practical applications.
  • Several recent reviews provide the scope and limitations of X-ray sensitive prior art resist materials:
  • positive resists exposed areas generally undergo a reduction in molecular weight with a consequent increase in the solubility of the exposed areas which can be preferentially removed by solvents or dry etching with unexposed areas remaining intact.
  • negative resists undergo cross-linking or other chemical changes upon exposure to various exposure radiations and become relatively resistant to removal by, e.g., solvents, in exposed areas when unexposed areas are removed.
  • PMMA polymethylmethacrylate
  • PMMA polymethylmethacrylate
  • poly(butene sulfone) because it has higher sensitivity (94 mJ/cm2), lacks resistance to oxygen reactive ion etching.
  • Another approach for improving resist sensitivity to X-rays has been to match the emission wavelength of the exposure source to the absorption band of a particular element in the resist.
  • U.S. Patent 3,893,127 discloses the use of certain copolymers of sulfur dioxide and certain olefins as electron beam resists.
  • U.S. Patent 3,898,350 discloses positive working electron beam sensitive polyolefin sulfone resist systems based on terpolymers formed from the reaction of an olefin and hydrocarbons selected from the group consisting of cyclopentene, bicycloheptene, an acrylate monomer and sulfur dioxide.
  • U.S. Patent 3,961,122 discloses a method of making thin polymer films comprising a synthetic aromatic base homopolymer, a copolymer, e.g., polystyrene or polycarbonate with an organosiloxane, and a solvent. Although no disclosure occurs of resist use, it is indicated that a film of the material will cross-link when exposed to ionizing radiation.
  • U.S. Patent 4,267,257 discloses a method of forming a shallow surface relief pattern in a poly(olefin sulfone) layer where the sulfone is poly(3-methyl-1-cyclopentene sulfone) and a modulated beam of electrons is used, image development then being conducted with a mixture of specific solvents. These materials lack oxygen reactive ion etch resistance.
  • U.S. Patent 4,289,845 discloses resist compositions comprising a matrix polymer in combination with a modified polymer where, in one embodiment, the modified polymer (phase compatible blend) comprises a novolac polymer and poly(2-methylpentene-1-sulfone).
  • U.S. Patent 4,341,861 discloses aqueous developable poly(olefin sulfone) terpolymers useful as positive resist recording media based on 3-methylcyclopentene, 2-cyclopentene-1-acetic acid and sulfur dioxide.
  • U.S. Patent 4,357,369 discloses a method of forming a pattern in a substrate by oxygen plasma etching techniques utilizing as a mask a poly(silane sulfone) copolymer resist.
  • U.S. Patent 4,396,702 discloses a method of forming a pattern in positive resist media where the resist is based upon poly(silane sulfone) copolymers.
  • U.S. Patent 4,398,001 discloses resist compositions formulated by combining a novolac resin with a poly(olefin sulfone) sensitizer which is a terpolymer synthesized from sulfur dioxide, an olefinic hydrocarbon and an unsaturated ether.
  • U.S. Patent 4,409,317 discloses a radiation sensitive coating composition containing, as a resin component, an alkali soluble resin and poly(2-methylpentene-1-sulfone). Isoamyl acetate or a mixture of isoamyl acetate with a compatible solvent is also introduced into the resin component.
  • European Patent Application No. 0005775 discloses the use of certain poly(olefin sulfones) as sensitizers in substituted low molecular weight novolac resins for lithographic applications.
  • Objects of the invention are radiation sensitive and at the same time oxygen reactive ion etch resistant compositions for application in integrated circuit device fabrication.
  • a further object of the invention is a lithographic process using said resist compositions.
  • Resist compositions are provided which are formulated by combining radiation sensitive polysulfones in silicon-containing resin matrices in suitable solvent systems. Thin films from these resist formulations are prepared according to standard processes involving application on desired substrates followed by a pre-bake step to remove the casting solvent.
  • Image-wise exposure of the dry film to radiation using conventional contact printing or projection printing techniques with an optional post-exposure bake followed by, e.g., solvent aided development of the thus post-exposure baked resist pattern provides effective and selective removal of the image-wise exposed or unexposed portions of the resist, depending on whether the resist is of the positive or negative type.
  • the resist pattern is subsequently transferred into an underlying polymer layer by, e.g., 0 2 reactive ion etching (RIE) when the imaging layer functions as an 0 2 RIE mask.
  • RIE reactive ion etching
  • the major object of the present invention is to provide novel resist compositions and processes of using the same.
  • novel resist compositions which exhibit one or more of the following characteristics: they are resistant to dry processing conditions, specifically 0 2 etching, which can be either plasma or RIE; they provide films of excellent quality with substantially no tackiness; they are highly sensitive to radiation, have good adhesion to a variety of substrates, and provide excellent resolution.
  • the polysulfones of the present invention are not unduly limited so long as they are thermally stable, i.e., do not undergo any significant decomposition below about 100 ° C and are compatible with the silicon-containing matrix resin in an appropriate solvent. Compatibility of polysulfone sensitizers in polymer blends is not a common phenomenon.
  • Suitable polysulfones according to this invention can be synthesized by copolymerization of olefins (linear, branched, cyclic) and/or allyl compounds with sulfur dioxide according to the general methods provided in the following references: "Polymer Synthesis", Chapter 1, Sadler and Karo, (1980); olefin polysulfone formation from a wide variety of olefins and allyl compounds is described by R.E. Cook et al in Journal of Polvmer Science, Vol. XXVI, pp. 351-364 (1957); N. Takura et al in J. Polvm. Sc., Part A, Vol. 1, pp. 2965-2976 (1963) and Vol. 2, pp. 3355-3363 (1964); and J. Himics et al in Polvmer Engineering and Science, Vol. 17, No. 6, June 1977.
  • the olefinic precursors used to form the polysulfones most useful herein include straight chain or branched 1-olefins, 2-olefins, cyclic-olefins and allyl compounds. These can be represented as follows: and have a total of 4 to 12 carbon atoms, e.g., where R can be H or CH 3 and Ri can be a linear hydrocarbon group with 2 to 10 carbon atoms, an ester group such as COOCH s , or an aromatic ring such as CeHs and pCH 3 CsH4. R 1 can also be a branched chain alkyl group.
  • Representative polysulfones include, e.g., poly(methylpentene-methallyl ethyl ether sulfone) synthesized by the process of U.S. Patent 4,398,001, hereby incorporated by reference, which is a terpolymer formed from the polymerization or sulfur dioxide, an olefin and an unsaturated ether, poly(2-methylpentene-1-sulfone), poly(butene-1-sulfone), poly(hexene-1-sulfone), poly(cyclopentene sulfone), poly-1-methylcyclopentene sulfone, propylene-methyl-methacrylate-S02 terpolymer, etc.
  • the poly(butene-1-sulfone) is commercially available (Poly Sciences) while others can be synthesized as cited above.
  • the molecular weight of the polysulfones can be freely varied. They preferably have a weight average molecular weight of from about 80,000 to about 300,000.
  • the silicon-containing polymers are not unduly limited. Normally we use silicon-containing polymers which have a glass transition temperature (Tg) greater than about - 25 ° C, preferably greater than about 50 ° C, and most preferably greater than about 100°C.
  • Tg glass transition temperature
  • the present invention should not be construed as limited to these Tg values, however. There is no maximum limitation on the Tg so long as such resins have the desired solubility in the solvent used and compatibility with the polysulfone additives so that no undesired phase separation occurs when the composite resin is applied to form thin films on various substrates.
  • the silicon-containing polymers have a glass transition temperature (Tg) as high as possible (keeping the solubility consideration earlier mentioned in mind) so that there is no image deformation or flow during the optional post-exposure bake and subsequent dry processing including conventional RIE and conventional metallization steps to be later described.
  • Tg glass transition temperature
  • the weight percent of the silicon-containing component(s) in the silicon-containing polymer preferably comprises at least about 6% as silicon, more preferably at least about 8% as silicon, by weight based on the total silicon-containing polymer.
  • the desirable characteristics of the matrix resin according to this invention are that it have solubility in the solvent used, be thermally stable, and have good film forming characteristics, i.e., it not yield a tacky film and the film comprising the same be uniform.
  • a further requirement for lithographic processing is that the same exhibits good adhesion to the substrate involved so that there is no adhesion failure or pattern lifting during solvent aided development of the exposed film.
  • Typical matrix resins useful according to this invention are alternating block polymers, block or random copolymers or terpolymers of diorganosiloxanes, silarylene siloxanes and the following non-silicon polymer segments: polycarbonate, polyester, polyurethane, polyamide, polyurea, poly(arylene ether), poly(alkylene ether), polysulfone as described in "Block Copolymers", Overview and Critical Survey, A. Noshay and J. E. McGrath, Academic Press, pp.
  • block copolymers are commerciaiiy available and are easy to synthesize according to standard procedures from commercially available starting materials.
  • the molecular weight of these resins can be freely varied considering the above characteristics.
  • the preferred molecular weight of the silicon-containing polymers e.g., a bisphenol A-poly- carbonate/polydimethylsiloxane block copolymer, and those later described, is about 100,000 to about 200,000, weight average.
  • the ratio of the polysulfone and the silicon-containing polymer can be freely varied so long as the polysulfone is present in an amount effective for generation of a high contrast pattern.
  • the polysulfone will be present in an amount of about 10 to about 30 wt% of the total polysulfone plus silicon-containing polymer.
  • a further benefit of the present invention is that, unlike resists based on a novolac matrix, the silicon-containing polymer matrix of the resist composition of the present invention is relatively transparent to various types of irradiation, including the deep-UV region, and thus permits one to use to full effect the sensitivity of the polysulfone to radiation, including the deep-UV region.
  • PDMS-silarylene or silphenylene copolymers ⁇ as is accepted in the art, the term "silarylene” denotes silphenylene in general including substituted silphenylene, e.g., methyl-substituted silphenylene), polystyrene-PDMS, poly-alpha-methylstyrene-PDMS copolymers, and hexamethylterephthalate-siloxane blocks.
  • silicon-containing polymers suitable for the purpose of this invention are: poly(tetramethyl-p-silphenylene siloxane) (PTMPS) and its copolymers with dimethylsiloxane, i.e., PTMPS/PDMS which can be synthesized according to well known procedures as described by N. Grassie and S. R. Beattie, Polym. Degradation & Stability 7 (1984), pp. 109-126; R. L. Merker, M. J. Scott and G. G. Haberland, J. Polym. Sci., A2, 31 (1964) pp. 31-44; PDMS-polyethylene oxide block copolymers; and PDMS-polyurethane copolymers. Most of these resin systems are commercially available, e.g., from Petrarch Systems as listed in .their "Silicon Compounds Register and Review", or can be synthesized using conventional procedures.
  • PTMPS poly(tetramethyl-p-silpheny
  • a preferred class of silicon-containing polymers includes poly(methylphenyl siloxanes), poly(tetramethyl-p-silphenylene siloxanes), polydimethylsiloxane-silphenylene copolymers, polydimethylsiloxane-alpha-methylstyrene copolymers, bisphenol A-polycarbonate-polydimethylsiloxane block copolymers, polydimethylsiloxane-styrene block copolymers, hexamethylterephthalate-siloxane block copolymers and polyurethane-siloxane block copolymers.
  • a preferred class of silicon-containing block copolymers includes those where the silicon-containing segments are polysilphenylenesiloxanes, polydialkylsiloxanes, polysilarylene siloxanes, and dimethylsiloxane, combined with non-silicon-containing segments from bisphenol-A-polycarbonate, polyurethane, polyester, polyimide, polyurea, poly(alkylene ether) and polysulfone.
  • silarylene or siloxane-containing copolymers e.g., poly(tetramethylsilphenylene) siloxane and silarylene-siloxane/dimethylsiloxane copolymers
  • both the segments or blocks in the polymer structure it is possible for both the segments or blocks in the polymer structure to contain silicon.
  • the resin formulations per the present invention are formed by dissolving the polysulfone(s) in a solution of the matrix resin prepared by predissolving the matrix resin in a solvent or a solvent mixture.
  • the resin components are dissolved at ambient temperature, though we see no reason why higher temperatures could not be used so long as the recognized sensitivity of polysulfones to heat does not become a problem. We see no advantage to using such higher temperatures at present.
  • the solvents are not limited and are typically organic solvents or mixtures thereof. Representative examples include chlorobenzene, toluene, isoamyl acetate, cyclohexanone, and dichloromethane (too low boiling point to be preferred). Obviously other solvents that will provide a homogeneous coating formulation of the polysulfone and silicon-containing resin can be used.
  • the concentration of the polysulfone and the silicon-containing resin in the solvent are selected so as to obtain a mutually compatible resist formulation and the concentration is not limited.
  • the total solids content can preferably vary from about 4 to about 10 wt% polysulfone and the matrix resin (based on solvent weight) to be convenient for film deposition by spin coating, spray application.
  • the coating formulations are filtered through a submicron filter prior to use to remove particulates or polymer gels which can be the source of film defects. This is a conventional step in the art. We normally use a 0.2 11m silver membrane (commercially available) to remove such particulates.
  • the dry thickness of the resist films per the present invention is not limited in any substantial fashion so long as the resist films are free of defects including pinholes and are optimum for processes requiring pattern transfer into underlying films having a, e.g., about a 1-5 J lm thickness.
  • thicknesses on the order of about 200 nm to about 800 nm provide excellent results, e.g., for pattern generation by radiation such as deep-UV lithography and subsequent image transfer into the base layer by 0 2 RIE.
  • the resist composition of the present invention can be applied onto any desired substrate in a conventional manner, e.g., spinning, dipping, spraying. Currently we prefer to use a conventional spin application.
  • Examples of the substrates for the resist process of the present invention include a variety of surfaces as are used in the fabrication of microelectronic devices, e.g., silicon, silicon oxide, silicon nitride, deposited according to conventional methods such as plasma, low pressure chemical vapor deposition (LPCVD) and plasma-enhanced chemical vapor deposition (PECVD).
  • LPCVD low pressure chemical vapor deposition
  • PECVD plasma-enhanced chemical vapor deposition
  • thicker underlayers formed from polymer coating compositions are employed and subjected to any desired or necessary conventional high temperature bake prior to overcoating with the resist formulation of the present invention.
  • the conventional materials for the underlayer typically include materials such as Shipley AZ-1350J, ICI polysulfone, soluble polyimides, typically those available from Ciba Geigy such as XU-218, and from General Electric Corp., such as GE ULTEM polyetherimide, which can withstand metal evaporation temperatures.
  • Conventional photoresists are often used as such an underlayer which is baked at temperatures higher than 200°C to render the film insensitive to optical or the image-wise exposure radiation used, e.g., UV radiation.
  • substrate is not limited to conventional inorganic substrates, but includes polymer surfaces for application of the resist composition of the present invention.
  • the resist composition of the present invention is particularly useful in a bilayer resist system where the resist composition of the present invention functions as an 0 2 etch resistant imaging layer and the conventional polymer underlayer as above-discussed is for image transfer through dry or wet processing so as to obtain a desired image depth and also functions as a lift-off layer for conventional metal lift-off processing.
  • the conventional polymer underlayer, in a bilayer resist system would generally be one amenable to oxygen etching, either plasma or RIE. It is not, of course, mandatory that the resist composition be used in a bilayer resist process and it can be employed in a single layer process or for mask making.
  • the latter is generally baked up to 200 ° C to 270 ° C prior to applying the resin composition.
  • This temperature is not limitative and the ambient of baking is not important, e.g., is typically air for a lower temperature (less than 100 ° C) while for a higher temperature such as 200 ° C to 270 ° C, an inert gas is employed.
  • Shipley AZ-1350J can be applied by spin coating in a conventional manner and then baked up to 230 ° C in, e.g., N 2 .
  • the time of baking is merely selected to insure that the earlier mentioned insensitivity is obtained.
  • the underlayer is first spin applied on the desired substrate, baked at 85°C for 20 minutes followed by 200 ° C(N 2 ) for 15 minutes and 230 ° C (N 2 ) for 30 minutes.
  • the resist composition of the present invention is applied and the film baked (pre-bake) at about 85-115°C for about 20-40 minutes and contact printed in a conventional manner using an appropriate exposure device, e.g., a Kasper UV exposure device for deep-UV.
  • the film is subjected to an optional but preferred post-bake at about 80-110 ° C for about 10-30 minutes, typically 105 ° C for 15-30 minutes, whereupon high resolution relief images are obtained.
  • Replication of the resist pattern into the underlayer is followed by metallization in a conventional manner, e.g., sputtering or vacuum evaporation, after standard premetallization cleaning steps. Lift-off is then accomplished in a conventional manner by, e.g., a solvent soak, to obtain the image-wise metal pattern for an integrated circuit device.
  • metallization in a conventional manner, e.g., sputtering or vacuum evaporation, after standard premetallization cleaning steps.
  • Lift-off is then accomplished in a conventional manner by, e.g., a solvent soak, to obtain the image-wise metal pattern for an integrated circuit device.
  • deep-UV radiation herein we mean ultraviolet radiation in the range of about 200 to about 300 nm, more typically about 200 to about 290 nm with commonly available commercial exposure devices.
  • the resist films according to this invention are also imageable by an excimer laser, e.g., 248 nm radiation.
  • exposure times/intensities can be optionally selected so long as the polysulfone is activated to provide the desired difference in removal characteristics between exposed and unexposed areas.
  • substantial cross-linking in the irradiated areas of the resist should be avoided, as will be apparent to one skilled in the art, i.e., cross-linking which would excessively inhibit removal of exposed resist areas.
  • usually greater resist thicknesses require greater exposure times and/or intensities, with the reverse being the case with lesser resist thicknesses. While not limitative, we have usually used exposure times of about 10 to about 90 seconds with an average exposure dose of about 10 to about 200 millijoules per square centimeter.
  • These resist materials also have high sensitivity to X-rays and electron beams and thus can be used for pattern generation with these techniques for lithographic processing.
  • the resist films of the present invention can be employed to generate either positive or negative patterns by varying the exposure dose.
  • the exposure dose For example, less than 0.5 J lm thick resist films of bisphenol A-polycarbonate-polydimethylsiloxane block copolymer having 20% (by weight) of poly(methylpentene-methallyl ethyl ether sulfone) upon exposure to an aluminum Ka X-ray source at 20-30 mJ/cm 2 followed by a brief post exposure bake and solvent development provide positive patterns.
  • the brief post bake is a preferred but not essential step.
  • the same films, when exposed to 120 mJ/cm 2 or a higher dose followed by development, provide negative patterns.
  • Resist films per the present invention have also been found to be imageable by electron beam exposure with very high resolution at relatively low doses. Less than 0.5 ⁇ m films, when subjected to electron beam exposure at 1.0 ⁇ C/cm 2 to 5 J lC/cm 2 followed by a brief post exposure bake at, e.g., 85-105 ° C, provided positive relief patterns with resolution down to 0.25 Jlm lines. Subsequent image development by suitable solvent(s) or dry etching techniques can be used for complete image development. The same films, when exposed to a dosage ranging between about 10.0 J lC/cm2 and about 15.0 ⁇ C/cm 2 or a higher dosage, followed by development, provide negative patterns.
  • the image can be transferred into an underlayer, which is generally organic, by dry processing during which the imaged resist acts as a mask.
  • X-ray or electron beam irradiation we mean X-ray or electron beam irradiation as is conventionally used in the art for resist exposure from any conventional source.
  • the resist of the present invention will exhibit either negative or positive characteristics.
  • the resist of the present invention will exhibit negative characteristics whereas at low exposure doses the resist of the present invention will exhibit positive characteristics.
  • Normally times can be freely varied, and typically we use exposure times on the order of about 10 to about 90 seconds.
  • the above exposure dose ranges of about 10 to about 50 millijoules per square centimeter to achieve positive resist characteristics and greater than about 120 millijoules per square centimeter up to about 200 millijoules per square centimeter are not absolute, i.e., between about 50 millijoules per square centimeter and about 200 millijoules per square centimeter there will be a gradual blending between negative and positive resist characteristics. Since we generally desire to obtain about a 70 to about a 80 wt% retention of resist in areas where resist is to remain, we most prefer, at present, to practice within the above ranges. Obviously, the higher the amount of resist retention, the better.
  • the percent resist retention decreases; if one practicing the present invention could accept a lower resist retention in areas where resist is to remain, practice outside the above ranges would be possible. For the precise applications we generally contemplate, however, the above exposure dose ranges provide best results.
  • the dosage ranges for positive working resists range between about 1.0 ⁇ C/cm 2 and about 5 li C/cm 2
  • the dosage ranges for negative working resists range between about 10.0 ⁇ C/cm 2 and about 15.O ⁇ C/cm 2 for good results. Higher dosages can be used for the negative working resists, but we see no advantage at this time to using higher dosages.
  • post-exposure baking As a general rule, we have found that better resolution and superior resist performance results using post-exposure baking. We believe that during image-wise exposure, e.g., to deep-UV radiation when a positive resist is involved, radicals are generated in exposed areas which remain until the time of post-baking and, if post-baking is conducted, superior radical degradation is achieved in exposed areas, volatile species are created which are removed in the post-baking and porosity in exposed areas will be increased to render solvent permeation into the exposed areas more efficient, whereby accelerated solvent-aided image development is obtained. For thicknesses as earlier exemplified, a post-exposure bake at up to about 80-110 ° C for about 10-30 minutes provides excellent results. The atmosphere of the post-exposure bake is not important and, to date, we have merely heated in air on a hot plate. Thus, while optional, the use of a post-exposure bake is highly preferred.
  • a dry development technique such as plasma etching in CF 4 -0 2 or, more preferably, use a solventaided development in a conventional manner, generally following exposure/post-bake. While most of our experience has been with solvent-aided development, we believe that both solvent-aided development and CF 4 -0 2 plasma etching will provide fully developed submicron patterns with a high aspect ratio.
  • solvent mixtures for development of deep-UV sensitive resists include 30 vol% isoamyl acetate in isopropanol (30 ml isoamyl acetate/70 ml isopropanol), with which we have had best results, or similar proportions of tetrahydrofuran in isopropanol or similar proportions of dichloromethane in hexane.
  • preferred solvent mixtures for development of X-ray and electron beam sensitive resists include hexane-acetone-ethylacetate which optionally may have a small amount of methylisobutyl ketone acid.
  • development according to the present invention can be aided by mild ultrasonic agitation so as to assist in resist removal in exposed areas, if desired.
  • a solution of a positive resist composition per the present invention (6 wt% total solids based on solution weight) was formed by dissolving, at a weight ratio of 4:1, a bisphenol A-polycarbonate-polydimethylsiloxane block copolymer (weight average molecular weight of about 150,000, Tg of about 160 ° C, about 35% of polydimethylsiloxane by weight of the copolymer) and poly(methylpentene-methallyl ethyl ether sulfone) (Mw 200,000) in chlorobenzene at ambient temperature.
  • a bisphenol A-polycarbonate-polydimethylsiloxane block copolymer weight average molecular weight of about 150,000, Tg of about 160 ° C, about 35% of polydimethylsiloxane by weight of the copolymer
  • poly(methylpentene-methallyl ethyl ether sulfone) Mw 200,000
  • the assembly was subjected to a pre-baking at 105°C for 30 minutes in nitrogen to provide a resist assembly (resist composition per the present invention and the Shipley 1350J base layer) having a total thickness of about 2.4 wm.
  • Image-wise exposure was then conducted with deep-UV for 45 seconds through a contact mask using a conventional Kasper deep-UV exposure system (ca. 45 sec. and 100 millijoules/cm 2 ).
  • the assembly was post-baked at 105°C for 30 minutes in air, providing a very clear relief pattern in the resist composition of the present invention.
  • the assembly was submerged in a solution containing 30% of isoamyl acetate in isopropanol for 3 minutes at room temperature to provide a fully developed positive pattern in the resist composition of the present invention.
  • a brief heat treatment was then employed to evaporate any retained solvent in the film and the pattern was transferred into the underlying Shipley AZ-1350J layer down to the substrate using a conventional 0 2 RIE process at 250-300 watts with 25 sccm oxygen flow.
  • the fully etched images had a final thickness of about 2.3 J lm, demonstrating that the resist composition layer per the present invention remained intact during 0 2 RIE and permitted transfer of the image into the Shipley AZ-1350 base layer.
  • a 50 wt% xylene solution of polydimethylsiloxane-alpha-methylstyrene block copolymer Mw 80,000-120,000) obtained from Petrarch Systems was diluted with toluene to form about a 10 wt% resin solution based on resin solids. To 200 g of this solution was added 2.5 g of poly(methylpentene-methallyl ethyl ether sulfone) - Mw -same as in Example 1, formed per U. S.
  • Patent 4,398,001 - to form a clear solution of a positive resist which was filtered per Example 1 and spin applied on silicon wafers to a thickness similar to that in Example 1, pre-baked in nitrogen at 105 ° C for 30 minutes and exposed to deep-UV as in Example 1 through a contact mask.
  • the exposed film was subjected to a post-bake at 105 ° C for 10-15 minutes in air, a high resolution relief pattern appeared which was developed down to the substrate by a brief dip in an isoamyl acetate-isopropanol mixture (30:70 parts by volume).
  • the resist image When used in a bilayer process, the resist image could be transferred into the underlayer by 0 2 RIE with the image layer functioning as an effective 0 2 RIE mask.
  • the filtered resist composition prepared as a solution in chlorobenzene described in Example 1 was spin applied on a silicon substrate and pre-baked at 105°C for 30 minutes in nitrogen to form about a 420 nm thick film (dry thickness).
  • X-ray exposure was conducted using a conventional aluminum K a X-ray source at 20-30 mJ/cm2 followed by a 10 minute post-bake at 85 ° C in air. A clear relief pattern was visible.
  • a subsequent soak for 1 minute at ambient in a mixed solvent system consisting of hexane-acetone-ethylacetate in the ratio 6:1:1 (volume), respectively, followed by a hexane rinse gave a fully developed positive pattern when the exposed area was preferentially removed.
  • a brief post development bake (10 minutes) at 85°C in air to remove the trapped solvent gave the remaining thickness of 320-340 nm with about a 20% loss of the unexposed area during removal of the exposed area.
  • Example 2 The process was repeated in a bilayer resist system using hard baked AZ 1350 photoresist as a thick underlayer following the procedure of Example 1.
  • the exposed and developed pattern (same as above) was post-baked as above and etch transferred into the bottom layer by 0 2 RIE at 25 sccm gas flow, 0.05 ⁇ bar gas pressure and 300 Watts RF power. Under these conditions the patterned resist provided an effective 0 2 RIE mask.
  • the filtered resist composition described in Example 1 was spin applied on silicon wafers as per Example 1 and pre-baked at 105 ° C for 30 minutes in nitrogen to form about a 420 nm thick film.
  • X-ray exposure using the same conventional exposure source as in Example 3 at 120-150 mJ/cm 2 followed by a post-bake at 80°C for 10 minutes in air showed a clear relief pattern.
  • the pattern had excellent dry etch resistance to 0 2 RIE and thus could be used as a RIE mask in a bilayer resin process.
  • Example 3 A subsequent solvent soak as in Example 3 or a conventional plasma development was used to provide fully developed patterns. The process was repeated in a bilayer scheme as described above for generating high resolution patterns in a relatively thick underlayer when the electron beam resist pattern provides the necessary 0 2 RIE resistant mask.

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • General Physics & Mathematics (AREA)
  • Materials For Photolithography (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)

Claims (18)

1. Réserve lithographique, caractérisée en ce qu'elle comprend un mélange d'au moins une polysulfone sensible aux radiations avec au moins un polymère contenant du silicium.
2. Réserve suivant la revendication 1, caractérisée en ce que la polysulfone est un copolymère formé par la polymérisation du dioxyde de soufre avec une matière choisie dans le groupe comprenant des 1- oléfines à chaîne droite, des 1-oléfines à chaîne ramifiée, des 2-oléfines, des oléfines cycliques et des composés allyliques.
3. Réserve suivant la revendication 2, caractérisée en ce que le copolymère polysulfonique est choisi dans le groupe comprenant une poly(2-méthylpentène-1-sulfone), une poly(butène-1-sulfone), une po- ly(hexène-1-sulfone), une poly(cyclopentène-sulfone) et leurs mélanges.
4. Réserve suivant la revendication 1, caractérisée en ce que la polysulfone est un terpolymère formé par la polymérisation du dioxyde de soufre, d'un hydrocarbure oléfinique et d'un éther insaturé.
5. Réserve suivant la revendication 4, caractérisée en ce que la polysulfone est une po- ly(méthylpentène-méthallyl éthyl éther-sulfone).
6. Réserve suivant la revendication 1, caractérisée en ce que le polymère contenant du silicium au moins présent est choisi dans le groupe comprenant des homopolymères, des copolymères, des terpoly- mères et leurs mélanges.
7. Réserve suivant la revendication 6, caractérisée en ce que l'homopolymère, le copolymère ou le terpolymère est composé de matières polymères choisies dans le groupe consistant en po- ly(méthylphényi siloxanes), poly(tétraméthyl-p-silphénylène siloxanes), copolymères de polydiméthylsiloxane-silphénylène, copolymères de polydiméthylsiloxane-alpha-méthylstyrène, copolymères à blocs de bisphénol A-polycarbonate-polydiméthylsiloxane, copolymères à blocs de polydiméthylsiloxane-styrène, copolymères à blocs d'hexaméthyltérephtalate-siloxane et copolymères à blocs de polyuréthanne-siloxane.
8. Réserve suivant la revendication 6, caractérisée en ce que le copolymère contenant du silicium est un copolymère à blocs comprenant des segments contenant du silicium, choisis dans le groupe consistant en polysilphénylènesiloxane, polydialkylsiloxanes, polysilarylènesiloxanes et diméthylsiloxane, combinés avec des segments ne contenant pas de silicium choisis dans le groupe consistant en bisphénol A-polycarbonate, polyuréthanne, polyester, polyimide, polyurée, poly(alkylène éther) et polysulfone.
9. Réserve suivant les revendications 1 et 8, caractérisée en ce qu'elle comprend un mélange de copolymère à blocs de bisphénol A-polycarbonate-polydiméthylsiloxane avec un poly(méthylpentène méthylal- lyl éthyl éther-sulfone).
10. Réserve suivant les revendications 1 et 8, caractérisée en ce qu'elle comprend un mélange de copolymère à blocs de polydiméthylsiloxane-alpha-méthylstyrène avec un poly(méthylpentène-méthallyl éthyl éther-sulfone).
11. Procédé lithographique, caractérisé en ce qu'il comprend l'enduction des compositions de réserve suivant l'une ou plusieurs des revendications 1 à 10 sur un substrat, la cuisson de la réserve, l'exposition selon une image à une radiation et le développement pour éliminer des portions d'image exposées ou non exposées de la réserve pour fournir ainsi un motif de réserve.
12. Procédé suivant la revendication 11, caractérisé en ce qu'après l'exposition selon une image à une radiation, la réserve exposée est soumise à une post-cuisson à une température d'environ 85°C à 115°C pendant d'environ 20 à 40-minutes, de préférence d'environ 80° et 110°C pendant environ 10 à 30 minutes.
13. Procédé suivant la revendication 11, caractérisé en ce que l'exposition selon une image est effectuée avec une radiation ultraviolette lointaine à une longueur d'onde d'environ 200 à 300 nm.
14. Procédé suivant la revendication 11, caractérisé en ce que l'exposition selon une image est effectuée avec une irradiation par des rayons X avec une dose d'exposition moyenne d'environ 10 à environ 50 millijoules par cm2 pour des caractéristiques de réserves positives, ou avec une dose d'exposition moyenne d'environ 120 à environ 200 millijoules par cm2 pour des caractéristiques de réserves négatives.
15. Procédé suivant la revendication 11, caractérisé en ce que l'exposition selon une image est effectuée avec une irradiation par un faisceau électronique avec une dose d'exposition moyenne d'environ 1,0 à environ 5,0 microcoulombs par cm2 pour des caractéristiques de réserves positives, ou avec une dose d'exposition moyenne d'environ 10,0 à environ 15,0 microcoulombs par cm2 pour des caractéristiques de réserves négatives.
16. Procédé lithographique suivant la revendication 11, caractérisé en ce qu'il comprend de plus le transfert du motif de réserve par attaque, de préférence par attaque par plasma ou par ion réactif, dans une sous-couche polymère.
17. Procédé lithographique suivant la revendication 16, caractérisé en ce qu'un métal est de plus déposé après élimination complète des portions d'image exposées de la réserve et que ce métal avec le polymère sous-jacent est éliminé dans les zones non exposées où la réserve est présente par une procédure d'enlèvement par solvant.
18. Procédé lithographique, caractérisé en ce qu'il comprend le dépôt des compositions de réserve suivant l'une ou plusieurs des revendications 1 à 10 sur un substrat, suivi d'une précuisson, d'une exposition selon une image à un laser à excimère à une radiation UV lointaine et d'un développement par solvant ou à sec pour éliminer complètement les portions d'image exposées de la réserve.
EP19860106714 1985-05-31 1986-05-16 Réserve lithographique et procédé l'utilisant Expired EP0211161B1 (fr)

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US73965885A 1985-05-31 1985-05-31
US739658 1985-05-31
US83635386A 1986-03-05 1986-03-05
US836353 1986-03-05

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FR2669442B1 (fr) * 1990-11-20 1996-06-28 Verger Desporte Ste Nle Ets J Procede de transfert d'images topologiques.
US5298367A (en) * 1991-03-09 1994-03-29 Basf Aktiengesellschaft Production of micromoldings having a high aspect ratio
EP0524759A1 (fr) * 1991-07-23 1993-01-27 AT&T Corp. Procédé de fabrication de dispositifs

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JPS59152A (ja) * 1982-06-25 1984-01-05 Hitachi Chem Co Ltd 画像形成性樹脂組成物
JPS5968735A (ja) * 1982-10-13 1984-04-18 Tokyo Ohka Kogyo Co Ltd 感光性組成物
GB8403698D0 (en) * 1984-02-13 1984-03-14 British Telecomm Semiconductor device fabrication

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